Use mul_add in var_axis for better accuracy

jturner314 · jturner314 · commit 219485d9ff3f · 2018-05-28T18:57:59.000-04:00
diff --git a/src/numeric/impl_numeric.rs b/src/numeric/impl_numeric.rs
@@ -167,7 +167,7 @@ impl<A, S, D> ArrayBase<S, D>
             azip!(mut mean, mut sum_sq, x (subview) in {
                 let delta = x - *mean;
                 *mean = *mean + delta / count;
-                *sum_sq = *sum_sq + delta * (x - *mean);
+                *sum_sq = (x - *mean).mul_add(delta, *sum_sq);
             });
         }
         if ddof >= count {

Original file line number	Diff line number	Diff line change
`@@ -167,7 +167,7 @@ impl<A, S, D> ArrayBase<S, D>`
`167`	`167`	`azip!(mut mean, mut sum_sq, x (subview) in {`
`168`	`168`	`let delta = x - *mean;`
`169`	`169`	`mean = mean + delta / count;`
`170`		`- sum_sq = sum_sq + delta * (x - *mean);`
	`170`	`+ sum_sq = (x - mean).mul_add(delta, *sum_sq);`
`171`	`171`	`});`
`172`	`172`	`}`
`173`	`173`	`if ddof >= count {`